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Brake squeal has been analyzed by finite elements for some time. Among several methods, complex eigenvalue analysis is proving useful in the design process. It requires hardware verification and it falls into a simulation process. However, it is fast and it can provide guidance for resolving engineering problems. There are successes as well as frustrations in implementing this analysis tool. Its capability, robustness and reliability are closely examined in many companies. Generally, the low frequency squealing mechanism is a rotor axial direction mode that couples the pads, rotor, and other components; while higher frequency squeal mainly exhibits a rotor tangential mode. Design modifications such as selection of rotor design, insulator, chamfer, and lining materials are aimed specifically to cure these noise-generating mechanisms. In GM, complex eigenvalue analysis is used for brake noise analysis and noise reduction. Finite element models are validated with component modal testing.

Analytical computer simulations were used to optimize and fabricate an Advanced Integrated Safety Seat (AISS) for frontal, rear, side, and rollover crash protection. The AISS restraint features included: dual linear recliners, pyrotechnic lap belt pretensioner, 4 kN load-limiter, extended head restraint system, rear impact energy absorber, seat-integrated belt system, and side impact air bag system. The evaluation and optimization of the AISS design was achieved through analytical simulations using MADYMO multi-body analysis software, LS-DYNA3D finite element software, and through LS-DYNA3D/MADYMO coupling. Frontal and rear impact sled tests were also conducted with physical AISS prototypes and baseline integrated seats to verify performance. Both the analytical modeling and the experimental sled testing demonstrated safety improvements over the baseline integrated seat.

Mechanical properties of as-rolled steels used in a vehicle vary with many parameters including gages, steel suppliers and manufacturing processes. The residual forming and strain rate effects of automotive components have been generally neglected in full vehicle crashworthiness analyses. Not having the above information has been considered as one of the reasons for the discrepancy between the results from computer simulation models and actual vehicle tests. The objective of this study is to choose the right material property for as-rolled steels for stamping and crash computer simulation, and investigate the effect of forming and strain rate on the results of full vehicle impact analyses. Major Body-in-White components which were in the crash load paths and whose material property would change in the forming process were selected in this study. The post-formed thickness and yield stress distributions on the components were estimated using One Step forming analyses.

This paper discusses the contribution of instrument panel systems in a European side-impact event. Systems studied include a conventional steel cross-car beam system and a glass-mat thermoplastic (GMT) composite system, evaluated in a body-in-white structure. A thermoplastic composite instrument panel system offers mass, cost, and recycling benefits, but its performance vs. a conventional steel cross-car beam system merited an engineering investigation. The comparison methodology used included a nonlinear dynamic side impact study with a moving, deformable barrier developed according to European Economic Community (EEC) standards. A finite-element model used in this study simulated the body-in-white structure, barrier structure and instrument panel systems. The resulting data include velocity, displacement and energy absorption levels of various components of the respective instrument panel systems.

Light metal alloys based on magnesium and aluminum are increasingly being pursued for various vehicle interior applications because of distinct advantages such as weight savings and potential parts consolidation. One such application of light metal alloys is the steering wheel, which is an important component of a safety system that is comprised of the driver-side airbag, steering wheel, the steering column and its attachment bracketry to the instrument panel and the vehicle body structure. For the airbag to function effectively as a restraint during a frontal crash, the steering wheel has to provide adequate support. In addition to the steering column which is designed to absorb energy, the wheel can also function as an energy absorber if so designed. One way of achieving this energy absorption is through plastic deformation of the wheel. Adverse material characteristics, however, make the energy absorbing steering wheel design, using light metal alloys, a sizeable challenge.

Lack of good sealing of the interfaces between the various components of the automotive powertrain can affect its functionality, performance and efficiency. The performance characteristics of a gasketted or sealed joint (or assembly) in the powertrain, are its sealability, the strength of the flanges under assembly loads and the long term bolt torque retention under material degradation due to creep. A CAE approach has been presented to design, evaluate and optimize automotive powertrain gaskets, seals and gasket/seal assemblies under assembly conditions. In this approach, the shape of the gasket/seal cross-section is optimized to maximize sealing pressure, and the gasket/seal assembly is optimized for its performance characteristics. The interactions between the gasket/seal and the flange materials under assembly loads govern the performance of the gasket/seal assembly.

Side mirror design optimization has been traditionally accomplished using an iterative design and testing process, often resulting in considerable costs in retooling operations, and causing significant delays in production. The ever increasing demand for high quality products has led major automotive companies to set high performance standards for side mirrors. These include structural, vibration, and aesthetic criteria, which affect the functionality and appearance of the mirror. The first two issues have been successfully addressed here using a fundamental design philosophy and a computer aided engineering approach. This approach has helped improve product quality, reduce the costs associated with redesign and retooling and minimize the development cycle time from concept to production.

An experimental method for nondestructive estimation of damage in joints due to high mileage degradation in cars is presented. The method estimates damage by comparing transfer functions of the same car at zero and at high mileage. The potential of the method is demonstrated analytically using a three dimensional concept Finite Element Model (FEM) of a car body to simulate the transfer functions of this car body at zero and at high mileage. The results demonstrate that the method is effective for identifying the damaged joints as well as the relative degree of degradation.

Finite element (FE) modeling is becoming an integral approach to the study of crashworthiness of vehicle structures and occupant interaction with the structure. Crashworthiness assessment of a vehicle using numerical techniques necessitates the development of not only an accurate and representative vehicle model, but also a robust occupant model. This paper describes the development of mathematical models to perform the complete side impact simulation. The fully developed model can be used to evaluate occupant compartment intrusion and to assess occupant protection countermeasures in various side impact scenarios. A baseline finite element model of the side impact dummy (SID) used in the United States safety regulation, FMVSS 214, Side Impact Protection [7], was refined and calibrated using dynamic material and sub-system test data. Lower extremity geometry was reverse engineered and suitable material models and joints were incorporated in the revised model.

A methodology to develop full-vehicle representation in the form of a finite element model for crashworthiness studies has been evolved. Detailed finite element models of two passenger vehicles - 1995 Chevy Lumina and 1994 Dodge Intrepid have been created. The models are intended for studying the vehicle’s behavior in full frontal, frontal offset and side impact collisions. These models are suitable for evaluating vehicle performance and occupant safety in a wide variety of impact situations, and are also suitable for part and material substitution studies to support PNGV (Partnership for New Generation of Vehicles) research. The geometry for these models was created by careful scanning and digitizing of the entire vehicle. High degree of detail is captured in the BIW, the front-end components and other areas involved in frontal, frontal offset and side impact on the driver’s side.

Federal motor vehicle safety standard (FMVSS) 201 [1] stipulates that tests have to be conducted on the upper interior of vehicles to estimate the head injury criteria (HIC) and comply with the requirements of limiting the HIC(d) value to be less than 1000. Multiple impacts at the same location may lead to high values in HIC(d) due to strain hardening of the sheet metal. HIC(d) value is not only dependent on the performance of the countermeasure, but also on the performance of sheet metal underneath the countermeasure. This paper addresses the effect of multiple impacts on the HIC(d) value using finite element analysis. One of the objectives of this paper is to bring awareness of the effect of multiple impacts on head impact performance among the test engineers. A systematic procedure is established to decide vehicle structure change during development testing.

Seat assessment is an important necessity for the growing auto industry. The design of seats is driven by customer’s demand of comfort and aesthetics of the vehicle interiors. Some of the few seat assessments are H-point prediction with H-point Machine (HPM); backset prediction with Head Restraint Measuring Device (HRMD); seat hardness and softness. Traditional seat development was through developing series of prototypes to meet requirements which involved higher costs and more time. The seat requirement of H-Point measurement is of focus in this paper. Though there are other commercial available software/methods to perform the H-point measurement simulations, the aim here was to assess the capabilities of an alternate Computer Aided Engineering (CAE) methodology using CAE tools - PRIMER and LS-Dyna. The pre-processing tools - Hypermesh and ANSA have been used for modeling and Hyperview tool used for reviewing the simulations.